1. Field of the Invention
The present invention relates to olefin resin-based articles having excellent gas barrier properties which are useful in packaging applications, such as in the protection of foods and electronic components.
2. Discussion of the Background
Packaging foods, electronic components, and other oxygen sensitive entities in a film or a container which suppresses oxygen permeation has been proposed for protecting the package contents from oxidation, thereby maintaining the quality of the contents for prolonged periods of time.
For example, JP-B-53-12953 (the term "JP-B" as used herein means an "examined published Japanese patent application") discloses a transparent flexible plastic film with low permeability to gases and moisture. This film comprises a flexible plastic film, such as polyethylene terephthalate, cellophane, nylon, polypropylene, or polyethylene, having a thickness of from 5 to 300 .mu.m and have a transparent thin layer of a silicon compound represented by the general formula Si.sub.x O.sub.y (wherein x is 1 or 2; and y is 0, 1, 2 or 3) formed on at least one side thereof to a thickness of from 100 to 3,000 .ANG..
JP-A-63-237940 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses a transparent film having gas barrier properties comprising the above-mentioned flexible plastic film and having a metal oxide layer comprising an oxide of at least one of the following elements In, Sn, Zn, Zr or Ti formed on at least one side thereof by sputtering. Additionally a transparent heat-sealable resin film is coated thereon.
When a film material made of a polar resin, such as polyethylene terephthalate, nylon or cellophane, is used in the above process, sufficient adhesion to an inorganic oxide film and satisfactory gas barrier properties are obtained.
However, when the above-mentioned inorganic oxide is deposited on the surface of a resin-based article comprising a non-polar resin, the inorganic oxide layer tends to become detached from the non-polar resin relatively easily, upon the application of external stress or heat to the molded article. This detachment is primarily due to inadequate adhesion between the non-polar resin-based article and the deposited inorganic oxide. This situation occurs particularly in cases where a heat sealable layer is laminated on the oxide-deposited non-polar resin molded article, when the article is used, when the laminated article (having a heat sealable layer) is fabricated into final form for bag making a cover sealing, when the container is filled, or when the container and contents are sterilized, such as in the production of pouch-packed foods. When detachment of the oxide layer occurs, the gas permeability increases and the practical utility of the article is severely decreased.
Therefore, it is desirable to provide a resin-based article having good gas barrier properties, which does not undergo detachment of the inorganic oxide layer from the resin-based article and thus retains its gas barrier properties during fabrication and use.